Research summary

The laboratory looks at metabolism of toxic metals by bacteria that may contribute to the bioremediation of contaminated soils and groundwater.

Research description

Have you ever come across a stagnant pool that smelled like rotten eggs when you disturbed it? Or, have you wondered why iron pipes corrode in soil? Both the smell and the corrosion are caused by the sulfate-reducing bacteria that derive energy not from oxygen, but from sulfate, which is reduced to hydrogen sulfide. Do these bacteria only cause problems? Probably not, because we believe they can assist bioremediation, the destruction of toxic contaminants in the environment. Since oxygen kills these bacteria, all work with them must be carried out in the absence of air. Obviously, none but the most committed (stubborn) would work with them.

We are investigating the genetics and metabolism of hydrogen, iron, and sulfate in these bacteria. Just how do they make energy and is hydrogen an important intermediate in their metabolism as well as a substrate? How do they corrode iron? Metallic iron can serve as reductant and the Fe2+ produced is water soluble, until it is irrevocably precipitated by the sulfide ions also produced by the bacteria. Are the bacteria caught in a vicious cycle of removing iron that they need for growth, by the sulfide that is produced during growth? Do they need an iron acquisition system to grow?

The laboratory is also looking at metabolism of toxic metals by these bacteria that may contribute to the bioremediation of contaminated soils and groundwater. These bacteria convert a soluble form of uranium to an insoluble form that precipitates from water. Can we understand how this occurs? Can we increase the rate that this happens? Is the insoluble form used or is it inert forever? Many questions drive the research. Our studies abound with Southerns, cloning, PCRs, transposons, and problems. What we need now is a little intelligent help in understanding these fascinating and challenging organisms.